JP2018187874A - Printing device and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing device comprising a plurality of print heads and automatically performing device adjustment, and the like.SOLUTION: A printing device comprises: a first head and a second head discharging ink onto a printing medium; a conveyance part conveying the printing medium; a camera imaging the printing medium; a carriage being mounted with the first head, the second head and the camera and moving; and a control part printing a third mark by the first head, imaging the third mark by the camera, adjusting driving of the conveyance part and the carriage on the basis of a result of imaging, individually printing a first mark and a second mark by the first head and the second head, imaging the first mark and the second mark by the camera, and adjusting ink discharge timing of the second head on the basis of a result of imaging.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a printing apparatus including a plurality of print heads, and more particularly to a printing apparatus that automatically performs apparatus adjustment.

  2. Description of the Related Art Conventionally, ink jet printers that perform printing on a print medium by ejecting ink from nozzles have been widely used. In such a printing apparatus, there is a possibility that printing defects such as printing unevenness may occur depending on the state of the apparatus. Therefore, it is necessary to appropriately detect the phenomenon and perform appropriate apparatus adjustment.

  In the case of a large apparatus, such an apparatus adjustment operation is generally performed by a maintenance man at the time of assembling or replacing the print head. In this work, the print output of the test pattern is visually checked, and each setting relating to the printing operation is made manually based on the result.

  As a related technique, Patent Document 1 below describes that a scanner is mounted on a carriage together with an ink cartridge and the scanner is calibrated.

JP 2005-53228 A

  However, conventional manual device adjustment is complicated and requires labor and time. Therefore, automation of the work is desired.

  The invention described in Patent Document 1 does not adjust the head mounting error.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a printing apparatus including a plurality of print heads, which automatically adjusts the apparatus.

  In order to achieve the above object, according to one aspect of the present invention, a printing apparatus includes a first head and a second head that eject ink to a print medium, a transport unit that transports the print medium, A camera that shoots a print medium, a carriage that moves with the first and second heads and the camera mounted thereon, a third mark is printed by the first head, and the third mark is shot by the camera. Then, based on the result of the photographing, the driving of the transport unit and the carriage is adjusted, and the first mark and the second mark are printed by the first head and the second head, respectively. A control unit that images the second mark with the camera and adjusts the ink ejection timing of the second head based on a result of the imaging.

  According to this aspect, the apparatus can be automatically adjusted regardless of the manual operation.

  Further, in the above invention, a preferable aspect thereof is that adjustment of driving of the transport unit and the carriage is performed based on a difference between a position of the photographed third mark and a reference position on a movement path of the carriage. It is characterized by that.

  According to this aspect, the position adjustment in the scanning direction and the sub-scanning direction can be easily performed.

  Furthermore, in the above invention, a preferable aspect thereof is that the first mark is a plurality of first line marks printed by ejecting ink at a first timing by the first head, and the second mark is The second head prints a plurality of second line marks by ejecting ink at a plurality of different second timings including the first timing at positions corresponding to the first line marks. The adjustment of the ink ejection timing of the second head is performed based on the second timing at which the second line mark closest to the corresponding position is printed.

  According to this aspect, the second head can be relatively adjusted based on the deviation from the first head.

  In order to achieve the above object, another aspect of the present invention provides a first head and a second head for ejecting ink to a print medium, a transport unit for transporting the print medium, and photographing the print medium. In the control method of a printing apparatus, comprising: a camera that performs, a first head and the second head, and a carriage that moves by mounting the camera, the third mark is printed by the first head, and the third mark And adjusting the driving of the transport unit and the carriage on the basis of the result of the shooting, printing the first mark and the second mark by the first head and the second head, respectively, The first mark and the second mark are photographed by the camera, and the ink ejection timing of the second head is adjusted based on the result of the photographing.

  Further objects and features of the present invention will become apparent from the embodiments of the invention described below.

1 is a schematic configuration diagram according to an embodiment of a printing apparatus to which the present invention is applied. FIG. 6 is a plan view schematically showing a mechanism portion 22 around a carriage 222. It is the flowchart which illustrated the procedure of the calibration process. It is a figure for demonstrating the position mark a and the adjustment by it. It is a figure for demonstrating a line mark and the adjustment process by them.

  Embodiments of the present invention will be described below with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention. In the drawings, the same or similar elements are denoted by the same reference numerals or reference symbols.

  FIG. 1 is a schematic configuration diagram according to an embodiment of a printing apparatus to which the present invention is applied. A printer 2 shown in FIG. 1 is a printing apparatus to which the present invention is applied. In the printer 2, the camera 221 is mounted on the carriage 222 together with the plurality of print heads 220, and apparatus adjustment (calibration) processing is executed when the print head 220 is replaced. In this process, the printer 2 prints a test pattern of a position mark (third mark) with a reference print head 220 (hereinafter referred to as a reference head, the first head), captures the test pattern with the camera 221, Based on the photographing result, drive adjustment of the carriage 222 and the paper transport unit 223 is performed. Thereafter, the printer 2 prints a plurality of line marks (first mark, second mark) shifted in timing with the reference head 220 and the other print heads 220 (hereinafter, other heads, second head) as test patterns. Then, the test pattern is photographed by the camera 221, and the ink ejection timing of each other head 220 is adjusted based on the photographing result. With these processes, it is possible to automatically adjust the printer 2 with high accuracy.

  As shown in FIG. 1, a printer 2 according to the present embodiment is a printer that executes printing on a print medium such as paper M in response to a print request from the host computer 1 or the like. It is a large inkjet printer used for printing posters.

  As shown in FIG. 1, the printer 2 includes a control unit 21 and a mechanism unit 22. The control unit 21 is a controller that controls each unit of the printer 2. Although not shown, the control unit 21 includes a program describing processing contents, a CPU (processor) that executes processing according to the program, a RAM, a ROM that stores the program, and an ASIC. Etc. The CPU performs each control by reading and executing a program stored in the ROM.

  The printer 2 includes a normal mode (print mode) and an inspection mode. In the normal mode, when receiving print data from the host computer 1, the control unit 21 controls a print head 220, a carriage 222, and a paper transport unit 223, which will be described later, based on the print data. The printing process requested in the above is executed. In the control of the print head 220, the control unit 21 ejects ink from a plurality of nozzles provided in the print head 220.

  In the inspection mode for device adjustment (calibration), the control unit 21 controls a mechanism unit 22 described later to print a test pattern, shoot the test pattern, and an image corresponding to the photographic result (image data). Processing, analysis of image data, and adjustment processing based on the analysis result are executed.

  Moreover, the control part 21 is provided with a function structure as shown in FIG. The control unit 21 includes a print control unit 210 and a calibration unit 211.

  When a print request is made to the printer 2, the print control unit 210 interprets the print data, and controls each unit of the mechanism unit 22 based on the interpretation to perform print processing on the print medium (paper M or the like). Run. In the inspection mode, the print control unit 210 prints each test pattern.

  The calibration unit 211 controls processing in the inspection mode described above. Specific processing contents by the calibration unit 211 will be described later.

  The mechanism unit 22 is controlled by the control unit 21 and executes a printing process in the normal mode and the inspection mode, an imaging process in the inspection mode, and the like. As shown in FIG. 1, the mechanism unit 22 includes a print head 220, a camera 221, a carriage 222, a paper transport unit 223, and the like.

  FIG. 2 is a plan view schematically showing the mechanism unit 22 around the carriage 222. The print head 220 includes a plurality of nozzles, and ejects ink from the nozzles to the paper M in accordance with instructions from the control unit 21 (printing control unit 210) to form an image on the paper M and perform printing.

  As shown in FIG. 2, a plurality of (here, six as an example) print heads 220 are provided and mounted on the carriage 222. As an example, six colors (cyan, magenta, yellow, black, light cyan, light magenta) are used here, and a print head 220 is provided for each color ink. The print head 220 can be removed (replaced) for each color, and therefore the error in the attachment position differs for each color print head 220.

  In the inspection mode, the camera 221 (photographing device) photographs the paper M, which is a printing medium, and generates an image (test pattern) printed on the paper M as image data. As shown in FIG. 2, the camera 221 is mounted on the carriage 222. Note that the camera 221 includes a CMOS sensor, a lens, and the like as an example. Although not shown, a light source is provided in the vicinity of the camera 221, and the light source illuminates for photographing with the camera 221. The light source irradiates light to the imaging target (imaging area) of the camera 221, and the light quantity is variable. The light source is composed of, for example, a plurality of LED lamps. It should be noted that it is desirable that the mounting position of the camera 221 is corrected to the correct position and that shooting be performed with high accuracy.

  The carriage 222 mounts the print head 220 and the camera 221 and moves them in the scanning direction (the direction of the arrow X in FIG. 2). The carriage 222 is driven along the carriage rail 224 by a drive source and a transmission device (not shown). The carriage 222 moves under the control of the print control unit 210 during printing or the like.

  At the time of printing, as shown in FIG. 2, ink is ejected from the print head 220 that moves in the scanning direction by the carriage 222 to the paper M that is conveyed in the sub-scanning direction (the direction of the arrow Y in FIG. 2). An image is formed on the sheet M.

  The paper transport unit 223 (transport unit) is a device that transports the paper M in the sub-scanning direction, and includes a transport roller, a driving source thereof, a transmission device, a transport path, and the like, although not shown. The paper transport unit 223 is driven by the control of the print control unit 210 during printing or the like.

  The printer 2 having the above-described configuration operates in the normal mode and the inspection mode as described above. In the normal mode, a print request (print data) is received from the host computer 1 or the like, and the control unit 21 (print control unit 210) controls each unit of the mechanism unit 22 in accordance with the print request, thereby printing on the paper M as a print medium. Do. Specifically, the print head 220 moves in the scanning direction, and ink is ejected onto the paper M conveyed in the sub-scanning direction to form an image. The printed paper M is discharged by the paper transport unit 223.

  In the inspection mode, as described above, device adjustment (calibration) processing of the printer 2 is executed under the control of the calibration unit 211. The process will be specifically described below. FIG. 3 is a flowchart illustrating the procedure of the calibration process. In the printer 2, the calibration process is executed when the print head 220 is replaced in order to adjust printing defects caused by the above-described print heads 220 (attachment positions and the like). Here, a case where calibration is performed for all (six) print heads 220 will be described. However, calibration may be performed only for the replaced print heads 220.

  In this calibration process, first, an adjustment process is executed for the reference head 220 (here, “K” print head 220), and thereafter, the other heads 220 are adjusted based on relative displacement from the reference head 220. Execute the process.

  When the inspection mode is activated by the operator operating the printer 2 or the host computer 1, the calibration unit 211 first uses the reference head 220 to shift the print head 220 in the entire scanning direction and sub-scanning direction ( (Error) adjustment starts.

  First, the calibration unit 211 prints a position mark on the paper M using the reference head 220 (step S1 in FIG. 3). FIG. 4 is a diagram for explaining the position mark a and the adjustment performed thereby. The cross mark shown in FIG. 4 is the position mark a. The position mark a is printed as a test pattern by the print head 220 (reference head) of “K” (black ink) at a position as shown in FIG.

  Next, the calibration unit 211 captures the printed position mark a with the camera 221 (step S2 in FIG. 3). Image data in the imaging region R generated by the imaging is transferred to the calibration unit 211.

  The calibration unit 211 analyzes the transferred image data and detects an error (Δx) in the scanning direction and an error (Δy) in the sub-scanning direction of the printing position by the reference head 220 (step S3 in FIG. 3). Specifically, the calibration unit 211 first detects the position coordinates (x, y) of the center of the position mark a in the transferred image data. The position coordinates (x, y) are distances in the scanning direction and the sub-scanning direction from any vertex of the rectangular imaging region R, as shown in FIG.

  Next, the calibration unit 211 detects the coordinates (x ′, y ′) of the center position of the position mark a ′ arranged at a predetermined ideal (correct) position (reference position) and the above-described detection. The difference between the actual position coordinates (x, y) is obtained, that is, Δx = x′−x, Δy = y′−y, and errors Δx and Δy are detected.

  Next, the calibration unit 211 uses the detected error Δx as a correction value for the movement amount during printing of the carriage 222, and the error Δy as a correction value for the conveyance amount of the paper M during printing by the paper conveyance unit 223. Then, it is stored in the nonvolatile memory of the control unit 21 (step S4 in FIG. 3). These correction values may be stored after the errors Δx and Δy are converted into parameter values used for controlling the carriage 222 and the paper transport unit 223. Further, the storage of the correction value may be a process of changing a setting value referred to by the print control unit 210 during printing.

  Next, the calibration unit 211 starts an adjustment process for the other head 220. First, the calibration unit 211 uses all the print heads 220 to print a plurality of line marks as test patterns on the paper M for each print head 220 (step S5 in FIG. 3). FIG. 5 is a diagram for explaining line marks and adjustment processing using them.

  FIG. 5K illustrates nine line marks (KP (1)-(9), first mark) printed by the “K” print head 220, which is the reference head 220. . These line marks by the reference head 220 are printed at the ink ejection timing (first timing) set in the print control unit 210 at that time.

  5 (Y) and (LC), nine line marks (YP and (1)-() of YP and LCP) printed by the print head 220 of “Y” and “LC”, which are the other heads 220, respectively. 9), the second mark). These other line marks by the head 220 are printed so as to coincide with the respective line marks by the reference head 220 in the scanning direction (left and right direction in FIG. 5). That is, the line mark YP (1) and the line mark LCP (1) are printed so as to be at the same position in the scanning direction as the line mark KP (1), respectively. The same applies to the other line marks (1) to (9).

  Further, in the case of the line mark by the other head 220, unlike the case of using the reference head 220, printing is performed by shifting the ink discharge timing for each line mark. Specifically, in the case of (5) of the line mark YP and (5) of the line mark LCP, as in the case of the reference head 220, the ink ejection timing ( Thereafter, printing is performed at the reference timing). In the line marks YP (1) to (4) and the line marks LCP (1) to (4), the timing is later than the reference timing, and as the distance from the line mark (5) increases, the reference is sequentially performed. Printing is performed at a timing when the difference from the timing becomes large. Also, in line marks YP (6)-(9) and line marks LCP (6)-(9), the timing is earlier than the reference timing, and the reference is sequentially increased as the distance from the line mark (5) increases. Printing is performed at a timing when the difference from the timing becomes large.

  Further, the line marks by the print heads 220 for each color are printed using a part of the nozzles provided in each print head 220 so as not to overlap in the sub-scanning direction (vertical direction in FIG. 5).

  Similar line marks are printed on the remaining print heads 220 of the other heads 220 (not shown in FIG. 5).

  Next, the calibration unit 211 captures the printed line mark with the camera 221 (step S6 in FIG. 3). The image data of the line mark generated by the photographing is transferred to the calibration unit 211.

  The calibration unit 211 analyzes the transferred image data and detects an appropriate ink ejection timing in each of the other heads 220 (step S7 in FIG. 3). Specifically, the calibration unit 211 sets the position of each line mark ((1) to (9) in FIG. 5) in the scanning direction for each of the other heads 220, and prints the reference head 220 (here, “K”). The line mark printed by the head 220) is compared with the position in the scanning direction of the corresponding line mark, and the line mark with the closest (close) position is selected. Then, the calibration unit 211 detects the ink ejection timing when the selected line mark is printed as the appropriate ink ejection timing of the other head 220.

  In the example shown in FIG. 5, in the case of the “Y” other head 220, the line mark YP (6) indicated by b in FIG. 5 is scanned with the line mark printed by the “K” reference head 220. Since the direction position is the closest (because they match), the ink discharge timing when the line mark YP (6) is printed is detected as an appropriate ink discharge timing.

  In the case of the “LC” other head 220, the line mark LCP (3) indicated by c in FIG. 5 is closest to the line mark printed by the “K” reference head 220 in the scanning direction. (Because they match), the ink ejection timing when (3) of the line mark LCP is printed is detected as an appropriate ink ejection timing.

  As described above, when proper ink ejection timing is detected for each of the other heads 220, the calibration unit 211 stores these ink ejection timings in the nonvolatile memory of the control unit 21 as correction values (FIG. 3). Step S8).

  These correction values may be stored after conversion into parameter values used for image processing of print data, output timing of ink drive signals, and the like. Further, the storage of the correction value may be a process of changing a setting value referred to by the print control unit 210 during printing.

  In this way, the apparatus adjustment process by the calibration unit 211 is executed.

  At the time of printing, the print control unit 210 controls each unit based on the stored correction value, and high quality printing is executed. Specifically, the movement amount of the carriage 222, the conveyance amount of the paper M by the paper conveyance unit 223, and the ink ejection timing of each print head 220 are controlled based on the correction value. In the control of the ink ejection timing, for example, when the proper ink ejection timing is shifted by 1 dot or more from the reference timing, image processing is performed to shift the image data in units of dots, and the shift is within 1 dot. In this case, a process for shifting the output timing of the nozzle drive signal can be executed.

  As described above, the printer 2 according to the present embodiment has the camera 221 mounted on the carriage 222, and is calibrated when the print head 220 is replaced based on the image of the test pattern photographed by the camera 221. Perform In the calibration process, first, the scanning direction and the sub-scanning direction are adjusted based on the position mark printed by the reference head 220, and then, based on the plurality of line marks printed by each print head 220. The ink ejection timing of each print head 220 is adjusted. Therefore, the apparatus adjustment of the printer 2 is automatically performed, and the labor and time of the maintenance man can be reduced. Further, calibration is performed efficiently and with high accuracy by the adjustment based on the reference head 220 and the relative adjustment based on the deviation from the reference head 220.

  Further, calibration can be performed relatively easily based on the position mark and the line mark.

  The protection scope of the present invention is not limited to the above-described embodiment, but covers the invention described in the claims and equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Host computer, 2 ... Printer, 21 ... Control part, 22 ... Mechanism part, 210 ... Print control part, 211 ... Calibration part, 220 ... Print head, 221 ... Camera, 222 ... Carriage, 223 ... Paper conveyance part, 224 ... Carriage rail, M ... Paper.

Claims (4)

A first head and a second head for discharging ink to a print medium;
A transport unit for transporting the print medium;
A camera for photographing the print medium;
A carriage that moves by mounting the first head and the second head and the camera;
The third mark is printed by the first head, the third mark is photographed by the camera, and the driving of the transport unit and the carriage is adjusted based on the result of the photographing, and the first head and the first The first mark and the second mark are printed by two heads, the first mark and the second mark are photographed by the camera, and the ink ejection timing of the second head is adjusted based on the result of the photographing. And a control unit. In claim 1,
Adjustment of driving of the transport unit and the carriage is performed based on a difference between a position of the photographed third mark and a reference position on a movement path of the carriage. In claim 1 or 2,
The first mark is a plurality of first line marks printed by ejecting ink at a first timing by the first head, and the second mark is printed by the second head by the first line. A plurality of second line marks are printed by ejecting ink at a plurality of second timings including the first timing at positions corresponding to the marks, and the ink ejection timing of the second head is printed. The adjustment is performed based on the second timing at which the second line mark closest to the corresponding position is printed. A first head and a second head for ejecting ink to the print medium; a transport unit for transporting the print medium; a camera for photographing the print medium; the first head, the second head, and the camera; A carriage control method comprising: a carriage that is mounted and moved;
The third mark is printed by the first head, the third mark is photographed by the camera, and the driving of the transport unit and the carriage is adjusted based on the result of the photographing, and the first head and the first The first mark and the second mark are printed by two heads, the first mark and the second mark are photographed by the camera, and the ink ejection timing of the second head is adjusted based on the result of the photographing. A control method characterized by that.

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